And I'm the troll?
In an attempt to keep this on topic, because surely a person capable of making a political argument can make it anywhere...
Urban counties typically have a higher population than rural counties. And we have more rural counties than urban counties. Thus, explaining your OP's confusion in how Biden got a record low in counties, but a record high in votes.
Land doesn't vote. People do.
And while the electoral college usually helps with big states versus smaller states; it is irrelevant if all urban counties, with a higher population, turn the state blue thus allowing Biden to win the electoral college. Which he did.
What is there to debate here, exactly?